Roasting-furnace.



T. D. MERTON.

ROASTING FURNACE.

APPLIOATIOH TILED JAN. 29, 1910.

1,022,961. Patented Apr.9, 1912.

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Patented Apr. 9, 1912.

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ROASTING FURNACE.

APPLICATION FILED JAN. 29, 1910.

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ROASTING FURNACE.

Patented Apr. 9, 1912.

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APPLICATION FILED JAN. 29, 1910.

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APPLICATION FILED JAN.29, 1910.

Patented Apr. 9, 1912.

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fly/4 UNITED STATES PATENT OFFICE.

THOMAS DANIELLS MERTON, OF GROVE MILL, WA'IFORD, ENGLAND, ASSIGNOR OF ONE-HALF TO HARRY MACKENZIE RIDGE, OF LONDON, ENGLAND.

ROASTING-FURNACE.

Specification of Letters Patent.

Patented Apr. 9, 1912.

Application filed January 29, 1910. Serial No. 540,763.

To all whom it may concern:

Be it known that I, THoMAs DANIELLS MEnToN, a subject of the King of Great Britain, residing at Grove Mill, VVatford, in the county of Herts, England, metallurgist, have invented certain new and useful Improvements in Roasting-Furnaces, of which the following is a specification.

This invention relates to improvements in rotary rabbled rectangular furnaces, and parts thereof, for roasting all classes of crushed or finely divided ores, pyrites, concentrates, slimes, (spent oxid suitable for the manufacture of sulfuric acid) and it consists in the novel arrangement and combination of parts more fully set forth in the specification and pointed out in the claims.

In all rotary rabbled rectangular furnaces hitherto in use, the rabbles are so positioned as to cut deeply into each. others field, the result being that a portion of more or less partially roasted ore is always carried back toward the feed end by the circular travel of the rabbles, where it mixes with the green ore being fed on to the hearth of furnace. This serious defect I have entirely overcome, by my method of placing the rabble shafts at regular and irregular distances from each other, whereby the ore, on one or more hearths, is rabbled in a series of zones. The number and area of such zones, are governed by the character of the ore being roasted.

My object is to divide the ore in its passage through the furnace, into a series of field areas, each of which shall form a zone, and. within which .the ore is completely rabbled and mixed together, and a return to the part of the field already traversed is completely prevented, so that once the ore passes out of the field of one zone onward to the next zone, it has definitely progressed to that zone, and cannot be carried back into the zone it has once left.

In order that my invention may be readily understood, I will describe it by referenc to the accompanying drawings in which Figure l is an elevation showing brickwork and gears partly in section of a 3 hearth furnace with 9 rabble shafts. Fig. 2 a plan of dust chamber and fines of Fig. 1. Fig. 3 is a plan of top hearth (Fig. 1) showing field areas forming the different zones, and rabbles commanding same. Fig. 4c is a vertical cross section on shaft A, Fig. 1.

Fig. 5 is a vertical cross section on shaft I, Fig. 1. Fig. 6 is longitudinal sectional elevation of discharge casting, showing Archimedean screw, top and bottom regulating slides, and ore discharge pipe with stop plates. Fig. 7 is top view of discharge casting of Fig. 6. Fig. 8 is cross section of Fig. 6. Fig. 9 is adjustable top slide for regulating ore discharge in Fig. 6. Fig. 10 is adjustable bottom slide for deflecting the ore either to hearth below or discharge pipe outside the furnace in Fig. 6.

I do not confine myself to the exact sequence of zones, as shown in the drawings herewith, nor to the exact area of such zones. That is to say, the area of the first zone, may embrace the first and second rabble shafts, and the next zone may be an area embracing one, two, or more rabble shafts; in a like manner the size of the furnace may be increased or decreased, to suit the variable classes of ores to be roasted.

The advantage of my method of rabbling, as described above, over a single rabble shaft furnace with a plurality of hearths, is that for an equal furnace area, the number of times the ore is dropped from one level to another is reduced about 50%, thereby to that extent reducing the amount of dusting from this cause. Also by having the area of each hearth chamber considerably in excess of that in the single rabble shaft furnace a further percentage of the dust is re-depos ited among the ore. And again, on account of the reduced number of hearths required by my method, I am enabled to build as an integral part of the furnace, a dust chamber over the top hearth, without unduly raising the height of furnace, thus reducing the dust to a minimum.

I will now describe my system as applied to a furnace, having a number of rabble shafts, forming zones of variable areas, in sequence of 1, 2, 3, 2, 1 rabble shafts to each zone, these zones being formed on one hearth of a plurality of superimposed hearths, in exactly the same sequence. lVhen erecting the furnace for certain classes of ores, it may be advisable to vary the area of any zone, or the number of zones, and increase or decrease the size of furnace accordingly. The ore is fed into the furnace (Figs. 1, 2 and 3) near the center, close to rabble shaft A, and is deflected in increasing circles to the periphery, by dependent rabbles from a rabble arm attached to shaft A, the field area of which I call the first zone. On the end of the arm attached to rabble shaft B, the oblique shaped rabble slightly cuts into the field of No. 1 zone, and withdraws the ore into the field of the second rabble shaft B, which together with the third rabble shaft C form the second zone; these shafts being so positioned as to cut well into eaclrothers field, completely mixing the ore within the field area of this zone.

The fourth rabble shaft D, is so positioned as to permit only the oblique rabbles 52 on the end of its rabble arm to cut slightly into the field of the second Zone, and at each revolution to take about an equal quantity of ore from same, which is thus gradually withdrawn into the third zone, the area of this zone being commanded by rabble shafts D, E, F, each of which is so positioned as to cut deeply into its neighbors field, and thoroughly to mix the ore at each revolution of the rabble shafts by means of the rabbles attached thereto.

The seventh rabble shaft G is so positioncd that the scooping 'abble 52 on the end of its rabble arm shall cut slightly into the field of the third zone in a similar man nor to the second and fourth rabble shafts B, D, and the ore is deflected into the field of the fourth zone, which is commanded by the seventh and eighth rabble shafts G, H.

The ore from the fourth zone is taken by the rabble dependent from the rabble arm attached to the ninth rabble shaft I, and is deflected into the field of the fifth zone. where it is constrained to travel in successive reduced circles to a central discharge, whence it may be conveyed by ixrchimedean screw 70 (Fig. outside the furnace: or if a plurality of hearths is required, the ore is dropped through a central discharge, such as the discharge shown at 68 in Fig. 6 to the hearth below, when the ore will pass through a series of zones in exact order as described above, but in reverse direction. and in a. like manner through a. plurality of hearths.

I have shown in Figs. 1, 2, 3, 4, a three hearth furnace, with staggered dust chamher on top, and with nine rabble shafts driven by worm gearing running in oil. in dust proof cases, each rabble shaft being quite free to expand or contract vertically, or by means of its jack footstep 82 adapted in any suitable manner to be raised or lowered without stopping the furnace and without any strain on the gears; but the furnace can be worked by bevel gearing if preferrei.

Each hearth has a separate feed M, and a separate discharge N as shown in Fig. 5, the latter being of novel construction. As shown in Figs. 6, 7, S, 9, 10, the discharge consists of a cast iron case N, with iron top slide which regulates the length of ore discharge opening 68. An Archimedean screw 70 driven at the required speed by means of wheel (39 delivers the ore out of the furnace through a discharge pipe 63 fitted with stop plates 64-" to minimize the admission of air, and consequent dusting occasioned thereby each stop plate is connterbalanced by means of an adjustable weight 6 which slides on bar 646 attached to same. The bottom slide can be drawn out so that the opening 65 which permits the ore to pass into discharge pipe (33 is closed, the ore being discharged through opening at 68 made by the partial withdrawal of slide 55.

The above arrangement of three hearths having separate feeds and discharges, is very suitable for very finely crushed iron or copper sulfids, slimes, or spent oxid, (from gas works), since these materials, from their excessive fineness, are liable to dusting, the latter being minimized by its removal out of the furnace by means of the Archimedean screw 70. But the arrangement of three separate hearths may be modified, when ores of a coarse mesh are to be roasted, so that the furnace can be worked as a single feed, the ore passing through each hearth in sequence to its final discharge out of the furnace; this is done by stopping the second and third feeds M, and the first and second discharge screws 70, and by drawing out of slides 55 in the first discharge, thereby closing opening (35, and discharging the ore at (58 to the hearth below, and by opening the discharge ports R near shaft A on the second hearth, thereby discharging the ore on to the third hearth. It is advisable to withdraw the screws 70 from case N, when not. in use.

hen the gases are required for sulfuric acid making the walls of the dust chamber are builtthick, to conserve the heat of the gases passing through same. To prevent the cooled rabble shafts from absorbing some of this heat they are protected by means of tubes 80, which are preferably made of good fireclay and well burnt.

The dust chamber is baffled by means of divisional walls 77, Fig. 2, the gases passing into the chamber by uptake [lacs 75, 75, then passing through divisional walls at openings 78, and in zigzag direction passing from one division to the other, on to the final exit at 79.

The dust deposited in the dust chambers is periodically cleaned out, which can be rapidly performed, either by means of ports 74-, or through discharge passages 70 to the hearth below, and then carried by the rabbles to the discharge screw 70 and delivered out of the furnace.

The furnace is well built and strongly held together by buckstays and tie rods. Doors 73, Figs. 1, t and 5 are faced and fit closely, thereby preventing the escape of gases. Seals 81 are placed over footsteps 82 to prevent the escape of gases or the admission of air at these parts; they are filled with fine clean sand or soot.

In placing the discharge casting N, Fig. 6, in position care must be taken to put it in perfectly level and upright, so that the Archim'edean screw shall. work truly, the flanges 61, Fig. 8, rest on brickwork of arch and the case N, Fig. 8, is builtinto same, and thereby securely held in position. By means of a light iron bar with a hook on its end, which fits holes 66 and 67 the flat steel slide 55, Fig. 9, can be freely moved in recess 56, Fig. 8, so as to regulate the amount of Ore entering the field of screw 70. The longitudinal opening below the slide is beveled outwardly at 57 to prevent the ore from hanging above the screw. The bottom slide 55, Fig. 10, has an opening (35 which permits the screw to discharge the ore into outlet pipe 63, Fig. 6, when the ore is to be discharged to the hearth below, this slide is withdrawn far enough to close outlet pipe 63 (the slide works freely in recess 58, Fig. 8) and by so doing leaves an opening at 68, Fig. 6, the sides of which are beveled outwardly to prevent the ore from hanging when discharged through same. The fireboxes or other auxiliary appliances for heating the furnace, not being directly connected with my improvements, are not shown or described because they do not aid in explaining such improvements.

Throughout the drawings like reference letters and numbers refer to like parts.

Having thus described the nature of my said invention and the best means I know of carrying the same into practical effect, I claim z- 1. In an ore roasting furnace the combination of a hearth, a plurality of rotatable shafts passing through the hearth, arms carried by the shafts projectingly over the hearth, and rabbles attached to and depending from the arms, the shafts being arranged in groups and positioned so that the distance between adjacent shafts of adjacent groups is greater than the distance between each pair of adjacent shafts in a group whereby the radial extremity of an arm carried by a shaft of one group slightly overlaps the ext-remity of an arm carried by the adjacent shaft of an adjacent group midway between the last said shafts, while the radial extremities of the arms carried by the shafts of a group deeply overlap each other, and the ore is rabbled in a series of zones of variable area from feed to discharge.

2. In an ore roasting furnace the combination of a plurality of superimposed hearths, a plurality of rotatable rabble shafts passing through the hearths, arms carried by each shaft and arranged to project respectively 'over each hearth, rabbles attached to and depending from the arms, means for feeding material in proximity to a rabble shaft, means for transferring material from one hearth to another hearth, and means in proximity to a rabble shaft for discharging rabbled material, the said rabble shafts being arranged in groups and positioned so that the distance between adjacent shafts of adjacent groups is greater than the distance between each pair of adjacent shafts in a group, whereby the radial extremity of an arm carried by a shaft of one group slightly overlaps the ext-remity of an arm carried by the adjacent shaft of an adjacent group midway between the last said shafts while the radial extremities of the arms carried by the shafts of a group deeply overlap each other, and the ore is rabbled in a series of zones of variable area from feed to discharge.

3. In an ore roast-ing furnace the combination of a dust chamber formed integrally with the furnace, a hearth arranged below the dust chamber, rotatable shafts passing through the dust chamber and hearth, tubes within the dust chamber incasing said shafts, ducts communicating with the dust chamber and hearth, arms carried by each shaft projectingly over the hearth, and rabbles attached to and depending from said arms, the shafts being arranged in groups and positioned so that the distance between adjacent shafts of adjacent groups is greater than the distance between each pair of adjacent shafts in a group whereby the radial extremity of an arm carried by a shaft of one group slightly overlaps the extremity of an arm carried by the adjacent shaft of an adjacent group midway between the last said shafts, while the radial extremities of the arms carried by the shafts of a group deeply overlap each other, and the ore is rabbled in a series of zones of variable area from feed to discharge.

4. In an ore roasting furnace the combination of a dust chamber formed integrally with the furnace, a plurality of superimposed hearths arranged below the dust chamber, rotatable shafts passing through the dust chamber and hearths, tubes within the dust chamber incasing said shafts, ducts communicating with the dust chamber and the hearths, arms carried by the shafts pro jectingly over the hearths, rabbles attached to and depending from said arms, the said rabble shafts being arranged in groups and positioned so that the distance between adjacent shafts of adjacent groups is greater than the distance between each pair of adj acent shafts in a group, whereby the radial extremity of an arm carried by a shaft of one group slight-1y overlaps the extremity of an arm carried by the adjacent shaft of an adjacent group midway between the last said shafts while the radial extremities of the arms carried by the shafts of a group deeply overlap each other, and the ore is rabbled in a series of zones of variable area from feed to discharge, means for feeding material to a hearth, and means for with drawing material from a hearth.

5. In an ore roasting furnace the combination of a dust chamber formed integrally with the furnace, a hearth arranged below the dust chamber, rotatable shafts passing through the dust chamber and hearth, tubes within the dust chamber incasing said shafts, ducts communicating with the dust chamber and hearth, staggered baffle walls having openings for gases arranged within the dust chamber, arms carried by each shaft projectingly over the hearth, and rabbles attached to and depending from said arms, the shafts being arranged in groups and positioned so that the distance between adjacent shafts of adjacent groups is greater than the distance between each pair of adjacent shafts in a group whereby the radial extremity of an arm carried by a shaft of one group slightly overlaps the extremity of an arm carried by the adjacent shaft of an adjacent group midway between the last said shafts, while the radial extremities of the arms carried by the shafts of a group deeply overlap each other, and the ore is rabbled in a series of zones of variable area from feed to discharge.

6. In an ore roasting furnace the combination of a dust chamber formed integrally with the furnace, a plurality of superimposed hearths arranged below the dust chamber, rotatable shafts passing through the dust chamber and hearths, tubes within the dust chamber incasing said shafts, ducts communicating with the dust chamber and the hearths, staggered baflie walls having openings for gases arranged within the dust chamber, arms carried by the shafts projectingly over the hearths, rabbles attached to and depending from said arms, the said rabble shafts being arranged in groups and positioned so that the distance between adjacent shafts of adjacent groups is greater than the distance between each pair of adjacent shafts in a group, whereby the radial extremity of an arm carried by a shaft of one group slightly overlaps the extremity of an arm carried by the adjacent shaft of an adjacent group midway between the last said shafts while the radial extremities of the arms carried by the shafts of a group deeply overlap each other, and the ore is rabbled in a series of zones of variable area from feed to discharge, means for feeding material to a hearth, and means for withdrawing material from a hearth.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

THOMAS DANIELLS MERTON. lVitnesses JOSEPH MILLARD, GEO. J. B. FRANKLIN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

